Common, noncancerous tumours that grow slowly within the muscular wall of the uterus

  • Most common between the ages of 35 and 55
  • More common in black women
  • Lifestyle is not a significant factor

Fibroids are nonmalignant growths in the uterus that consist of muscular and fibrous tissue. Fibroids are found in up to 1 in 3 women of childbearing age in the UK and are more common in black women. Fibroids occur singly or in groups and may be as small as a pea or as big as a grapefruit. Small fibroids may not cause problems, but larger ones may affect menstruation or fertility (see Female infertility).

What is the cause?

The cause of fibroids is unknown, but they are thought to be related to an abnormal response by the uterus to the female sex hormone oestrogen. Fibroids do not occur before puberty, when the ovaries begin to increase oestrogen production, and usually stop growing after the menopause. They also increase in size when there are increased levels of oestrogen in the body, such as during pregnancy, although they do not seem to be affected by the combined contraceptive pill or hormone replacement therapy.

What are the symptoms?

Most small fibroids do not cause symptoms, but the common symptoms of larger fibroids include:

  • Prolonged menstrual bleeding.

  • Abdominal pain during periods (see Dysmenorrhoea).

  • Heavy bleeding during periods (see Menorrhagia).

Heavy blood loss may lead to anaemia, causing pale skin and tiredness. Large fibroids may distort the uterus, which can sometimes result in infertility and possibly in recurrent miscarriages. During pregnancy, a large fibroid may cause the fetus to lie in an abnormal position (see Abnormal presentation). Fibroids may also press on the bladder, causing a need to pass urine often, or on the rectum, causing back pain. Rarely, a fibroid may become twisted, resulting in sudden pain in the lower abdomen.

How are they diagnosed?

The doctor will perform an abdominal and internal pelvic examination to look for the presence of fibroids in your uterus. You may also have ultrasound scanning of the uterus or a hysteroscopy, in which a viewing instrument is inserted into the uterus through the cervix. A sample of the fibroid may be removed during the hysteroscopy to check that the growth is not cancerous. Sometimes, fibroids show up on X-rays that are taken for other reasons.

What is the treatment?

Small fibroids often do not need treatment but should be checked regularly by your doctor to make sure that they have not grown. If small fibroids need treatment, they may be removed during a hysteroscopy or by a laparoscopy, which is performed under general anaesthesia. Fibroids that are large and/or are causing symptoms may be removed via an incision in the abdomen. Before having the surgery, you may be prescribed hormones that suppress the production of oestrogen so that the fibroids shrink. If you have persistent, large fibroids and do not want children, you may consider having a hysterectomy.

Removal of fibroids usually results in regained fertility, but in about 1 in 10 women fibroids recur. Fibroids usually start to shrink after the menopause, when oestrogen levels in the body fall.

Test and Treatment: Hysteroscopy

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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